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L. SHAFIRO April 17, 1928.

ELECTROMAGNBTI C TRANSLATI NG DEVICE Filed April 11. 19?:

INVENTOR LAZARUS SHAPIRO BY ATTORNEYJ BEE-m Patented Apr. 17, 1928.

UNITED STATES PATENT OFFICE.

LAZARUS SHAPIRO, OF NEW YORK, N, Y.

ELECTROMAGNETIC TRANSLATING DEVICE.

Application filed April ll, 1927.

of m invention to provide improved means for holdin the armature andimproved methods assembling and adjusting the same.

In devices of the type to'be-described, it is common to mount thearmature on a spring, usually of the torsional type. Heretofore, themanner of mounting such a spring has given rise to considerabledifficulty in adjusting the position of the armature between the polepieces, one reason for this difficulty being that in making theadjustment operation the spring would become slightly flexed andtherefore would nullify the attempts atadjustment by'again assuming itsunstrained position upon completion of the supposed adjustmentoperation. By virtue of my improved construction, however, I am enabledto adjust the-armature both rotativel and by movement of translation inits p ane of vibration so as to accurately position same with respect tothe pole pieces and without straining the supporting spring.

A further object of the invention is to provide improved means forattaching the drive rod to the armature whereby the leverage obtainedmay be suitably reduced or otherwise varied. My invention furthercontemplates an improved support for the drive rod whereby such supportofi'ers suhstaw tia-lly no impedance to the movement of the rod.

, A further object is to provide an improved coil mounting which shallprevent the coil from rotating and from getting out of place.

Other objects and advantages of the invention will be apparent as thedescription proceeds, such additional features being specificallypointed outin the claims.

In the drawings, Fi ure 1 shows in assembled form an illustratlveembodiment of my invention, parts being broken away and in section;

Serial No. 182,555.

Figure 2 is a top view of the device shown in Figure 1, the coil housingbeing broken away;

Figure 3 1s a side view'- seen from the right of Figure 1, the conehaving been re moved;

Figure 4 is a sectional view'taken on line 4-4 of Figure 1;

Figure 5 isa view 'taken on sectiofnf55 of Figure 4; i Figure 6 is asectional view taken on line 6-6 of Figure 4; I

Figure 7 1s a perspective view of the armature and supporting spring,and

Figure 8 is a coil.

Referring now to the drawings in detail, 10 denotes the permanentmagnetusual in devices of this type to which areatt'ached the polepieces Band 14, bolts 11; Hand" nuts 12, 12 serving for this purpose.jConveniently, the shanks of bolts 11 adjacent the headsthereof are madeof square cross section, accommodated by square openings in pole pieces13 and '14. as shown, in order that the nut 12 may be screwed tightwithout turnin the shanks.

In t e preferred form of the device the pole pieces 13 andl l are'ofapproximately horseshoe shape and juxtaposed so as to pro vide a spacein which is mounted the armature 16 (and the armature coils), leaving ateither end of the armature two air gaps of small dimensions, one on'eachside of the armature. The region of the pole pieces opposite thearmature ends form poles 17, 18, 19 and 20 respectively. It will thus beseen that in the present form of construction there are four air gaps,one between each pole and the armature. The adjustment of-these gaps toexact quality and predetermined length is one of the main features ofthe present invention, this adjustment being one of the most importantfactors in determining the performance of a device of the char-' acterreferred to in the present application.

Armature 16 is mounted preferably on a flat torsional spring 22, beingsuitably secured to said spring in preferably the following manner:Spring 22 is made in two halves 22, 22", Which partially surroundarmature 16 and are soldered thereto. It will be obvious that variousother means forming'no part of the-present invention may be emplan v1ewof an armature 20 iing po les'l-t) and 20 i Screvvs 26, 271, 28. and

ployed to secure the armature 16 to the spring 22, as by having thespring in one piece and passing the armature through an aperturetherein.

The preferred composite armature support forms a rectangular Z as shown.It will be noted that in the preferred embodiment under description,spring 22 has flat portions or arms 22, 22 extending at right angles toits own plane and in planes parallel to that of: thevibration ofarmature 16, the significance and importance of which will be dealt withhereinafter. Arms 22 and22 are respectively secured to the device by meai b ock 24 an 5, (we Q j 24, is best seen in Figures 2 and 6. Bloel s24:,125,- vv ih-ieh-are otbrass or other m n-magnetic material, engagepole pieces 13 and 14,

,iblock, 24;, fog. example, being seour-eqLto a nd bridging poles 17 and1S and block engag- 29 pass through poles JVT-ZOJrespQCtiX-eiy,sene-vvsQfiand' 2'Z-being threaded into-block 24, and sew- 528 and (29into block .25, reference-to -Eigure l showinglthis construction.

As shown in Figure 5 pole pieces 1 3 and H aneeppovided with fourslight-1y elongated slots -30; for. accommodating screws 26-29respectively, the slot construct-i on being i for adjustment purposesas. will be gone into more tully below. i

Enough of'zthe device has been described ,for; an-understanding of themode'of assembling-the-armature and the ,adjustment of theai r gaps towhich my invention is largely directed. In assembling the device, thearmature coils 32 and 33 (to be described in grbat'err'detailhereinafter-)- are first. placed aro nd armaturelfir Shims35, 35- ofl-iorse- .shoe, shape as shown and of a thickness equal tor-that of:the. desired air gaspare. then Placed in position as. shown in Figure 5.the screws- 2-6-28 inclusive, inserted and preterablr screwed in partlyso; as to'holrd the pole pieces 13 and l4"slidably in place and theioregoing assembly of devices placed within a fixture having clampingmembers diagrammatically indicated by thearrows to the righ t and :leftof Figure 5. By such means pressure is applied longitudinally. of thepole pieces it being noted that due to the slots 30 in the pole piecesaccommodating screws 26 to29. inclusive, the pole pieces 13 and 1% willbe pressed tightlyagainst the shims separating the armature-=16 andpoles 1 7 20, thereby establishing positively the desined positions ofthe armature and the 'pole pieces-relative to each other. After, pressure is applied in this way the screws 26-- 28 are tightened and thussecure the armature and the pole pieces permanently in their properrelation to one :another. It will be n l ed-that theiarms 22. and 229oi; the spring .22, are also provided-at their ext-remities withtransversely extending elongated slots,

22 and 22 respectively, these slots registering respectively withcentral, threaded bores in each of blocks. 24 and 25, each recompletelyto accommodate itself between the gaps occupied by this ,sh'irns withoutsetting. up, torsional o1f,;tra@verse stresses or deformations e the,spring. Accordia y; ,x'vhile the parts wh n n their car-- nt -p d rmi slvsi iw bythe; d mp:

- s' i ev t h wn) s rew 5 m- ,clusive and 37, 37, are. screwed tight?The clamps are then remov d and the shims are pulled out, whereuponheparts remain permanently secured in their proper relative positions Ifdesired the above procedure may be varied someivhat by first permsnently attaching spring 22 to the respective hlocks2 t, 25 and theentire adjustment obtained-by means of serews 2629 inclusivebindingtheibldeks-to the pole ieces.

From theforegoingit Wll be seen that when aspring. of torsional typeused, an adjustment movement in a single direction isls uificientto,ailiust the armature both i rotatively about axis of vibrationran'd inecessary. in a movement of translation in the same planer. These txvomovements are Suflicient is than; .complete adjestrnent. O tl erwiseexpressed, the above described met liod of adjustment involves merelythe placing of the armature n" its correct. positionvrit-lgi respect to.pole pieces, s by shims (or other e. g. visual means) whi e the-support{on such armature is free to assume such position as will, and thenmerely tightening the screws securing such support to the device withoutin any Way disturb ng the assumed position of the armature support or inany w altering the tension oi the. armature spring. Y

It now remains to describe certain fur ther element's exemplifying otherfeatures 1 of the invention. Armature lt3 sec Figure and armature coilsare now attached to the i magnet by means of bolts 11 already doscribed.

A. further feature of my lIlVCIlti'fli consists in novel means ofsupporting the drive rod 43, consisting in a member 47 (Figure 3) ofspecial shapewhich is held in place one of the bolts 11 and preventedfrom rotation by means of an inwardly extending tab 48 (Figure 5) enaging whole or recess 49 in polepieoe 14. upport 47 has a downwardly(from the position shown in the drawing extending portion or arm havingapertures 50 adapted to have drive rod 43 pass through them, theseapertures registering substantially with notches 41 on offset ofarmature 16. Element 47, which is of light, flexible material will bethus seen to afford a complete support for drive rod 13 while in no wayinterfering with the movement of the armature or drive rod. Drive rod4-3 is joined to cone by means of the usual set screw construction 52.

One'of the important results obtained by the above described arrangementis' the fact that the three notches 41 and the three holes enablethemanufacturer to control the effective mass of the cone as transmitted toa variance of opinion regarding the desirable range of frequencies to becovered by a good lou speaker. By securing the drive rod in theoutermost notch, for example, the trans;

ferred mass of the cone is increased and the fundamental frequency islowered together with the whole range of frequencies repro duced; andvice versa, by choosing the innermost notch, the range of frequencies isshifted toward a higher pitch.

The armature coils 32, 33 also present a feature of the invention inthat they a re pro vided with an exterior casing somewhat larger thanthe opening between the sections 13 and 14 of the pole plate and havenotches 56, 57 which en age the inner sides of the. pole pieces, thiseing best seen in Figure 4. Pole pieces 13 and 14 are also constructedso as to maintain the armature coils separated by the proper amount,such COl'lSiJ'llCl-iflll involving the use of lugs 58, 5.) extendingfrom the inner sides of the pole. piece. -soc Figure 5. A housing ispreferably provided for the coil and armature attaching means, suchhousing being preferably constructed of two halves 60 and G1 which areplaced on opposite sides of the pole pieces and clamped against the polepieces by means of bolts 62, 63. Within the casing on one of the halvesthereof I have the usual terminal connections 64:, 65 properly insulatedand connected to the ends of the composite coil.

I wish it understood that various details; of the aborc describedembodiment may be considerably varied without departing from the spiritof my invention.

lVhat I claim is:

1. In an electro-magnetic translating device having an air gap, anarmature co-operating with said gap, a mounting for said armature, aportion of said device and said mounting having coopera-ting surfacesex-' 7, tending parallel to the plane of vibration of the armature, andmeans for securing said mounting to said portion of the devicepermitting relative movement of said co-operating surfaces to permit ofadjustment of the armature in said plane of vibration.

2. In an electro-magnetic sound translating device having an air space,an armature extending within said space, a mounte ing for said armaturecomprising a spring" having attaching portions which includev clampingsurfaces parallel to the plane of vibration of the armature, and meansfor securing said portions to the device permitting adjustment movementof the arma turc both.of translation and of rotation in its plane ofvibration.

3. In an electro-magnetic sound translating device having pole piecesproviding an air space, an armature extending within said space, amounting for said armature comprising a spring having an attachingportion extending parallel to the plane of vibration of the armature,and common means for securing to eachother the pole pieces forming theair space and said attaching portion.

4. In an electro-magnetic translating device having two pairs ofoppositely'disposed f poles providing a pair of air spaces, an armaturehaving its ends extending within said spaces, a mounting for saidarmature comprising a spring intermediate the ends thereof, said springhaving oppositely extending attaching arms which are paral- 11o lcl tothe plane of. vibration of the armature, and common means for attachingone of said arms and a. pair of said poles in adjusted relation.

5. In an electro-magnetic sound translating device, a mounting for anarmature comprising a spring member of rectangular Z shape, said springmember sustaining the armature intermediate and substantially parallelto the arms of the Z.

G. In an electro-magnctic sound translating device, a mounting for anarmature comprising a spring member of rectangular Z shape, said springmember sustaining the armature intermediate and substantially 125parallel to the arms of the Z, the ends of said mounting havingtransversely extendin slots for attaching same to the device I. Incombination, an armature for an electro-magnetic translating device, sal1:10

armature having an ofl'set poi-(ion at right angles to its plane ofvibration and adapted to have a, vibrator drive rod attached there to inproper posit-ion intermediate end of said armature and its transverseaxis, a support'for said; drive rod comprising an arm spaced from saidarmature and means for attaching said support to said device.

8.;I-n eomhination, an armature for an eleetroimgignet c translatingdevice, said armature having an QfiSCt portion at right.

gngl es its plane of vibration and Adapted (.0 have a vibrator drive rodattached thereto in proper position intermediate uri efid of saidarmature audits transverse axis and a support or said drive rodcomprising" a depending arm spaced from szii d errn e'ture,

and having apertures through one of v vhjieh the drive rod is adapted topass, depending upon the adjusted position of said drive 1 5 Intestimony whereof I have affixed signature to this specific ation.

LAZARUS. S A IEQ I

